An open hierarchical data structure (U.S. Pat. No. 5,630,125 Zellweger) produces a highly efficient menu-based retrieval technology. Zellweger (1997) identifies this easy to use, end-user retrieval technology as a content menu. In contrast to prior retrieval technologies, the structure organizes information and its content menu works like an index in the back of a book, using a list of lists to locate information. The primary advantage of the content menu is that it shows end-users what they can expect to find in an information system.
However, the only way to build an open hierarchical structure, until this disclosure, was by hand. That is, each node and menu entry had to be added to the structure, one at a time. This was consistent with prior menu management art, Brandt (U.S. Pat. No. 5,261,042) and Eprath et. al. (U.S. Pat. No. 5,041,967), but for a particularly large or richly detailed content domain, the lack of automated ways to generate menu data makes this particular approach labor intensive and expense.
Prior art to building hierarchical data structures from conventional database sources has been disclosed by Simonetti (U.S. Pat. No. 5,295,261 Apr. 15, 1994). Input data is derived from columns in a database table that all share a "natural hierarchical ordering" like columns storing information on "country, states, counties, and cities". This approach reduces storage and makes searches more efficient. To broaden query capabilities one hierarchical structure is merged with another using a common set of nodes that intersect like "cities" or "states". The result produces a structure that provides "topological map" of the database that can be navigated to help answer specific queries. However, the new structure in this art no longer functions like a conventional hierarchical access method, and it can only be used by an expert who understands both the database content and relational database technology.